1. Field of the Invention
The present invention relates generally to apparatus and method for trimming cylindrical articles, and more particularly to apparatus and method for longitudinally trimming can bodies to a predetermined length and efficiently disposing of the waste portion trimmed at high speeds.
2. Description of the Prior Art
A number of devices and methods for trimming excess material from cylindrical articles, and particularly from two piece can bodies formed by a drawing and wall ironing process are known. Conventionally, aluminum or steel cans are formed by flowing the metal in the wall of the can until the can wall thickness is quite thin. This produces an uneven end and excessive length which requires that the excess material be accurately trimmed from the open end of the can body. Of course trimming per se is a simple severing operation. However, as a result of can lines operating at rates in excess of 600 to 800 cans per minute, problems have been encountered in disposing of the excess material trimmed from the end of the can body. Commonly, this small strip or annulus of material falls into the machinery to jam and even break the mechanism.
Yann U.S. Pat. No. 3,481,232 is an example of an apparatus which, on the surface may appear similar to that of the instant invention, but which, in fact, operates on an entirely different and more complicated principle. The Yann mechanism involves apparatus to push a can axially onto a spindle and thereafter to encounter a fixed arcuate knife blade. However, the spindle and can are of such dimensions as to provide an angular relationship between the spindle and can as it moves onto the spindle. Thus the arcuate knife blade encounters the leading edge of the can and cuts in a spiral manner to remove the excess material. Accordingly, the Yann Process does not sever by shearing an annulus which may be controlled by a portion of the mandrel but instead produces initially a strip of material which is not positively located and accordingly is subject to jamming.
Armbruster et al U.S. Pat. No. 3,400,620 discloses a somewhat similar diagonal cutting trimmer apparatus which provides strips rather than annular scrap portions. Further, the Armbruster et al apparatus utilizes retractable knife blades which are mechanically extended and retracted at various portions of the operation. Thus a very complicated cutting arrangement is involved.
Windstrup U.S. Pat. No. 3,548,769 discusses a carriage mechanism in which the tubular members are carried to individual work stations at which specific processes are accomplished. Among the work stations are an axially reciprocal trimmer which engages and trims the can. However, in view of the indexing and work station approach disclosed by Windstrup, high speed operation is not readily obtained with an apparatus of this type.
Maytag U.S. Pat. No. 3,425,251 and Larkin et al U.S. Pat. No. 3,838,653 disclose somewhat similar devices for trimming can bodies. In both cases, the cans are engaged on a rotating mandrel. However, trimming is accomplished by a rotating knife blade which engages the mandrel and requires, for instance, an expandable mandrel in one instance, and critical alignment and spacing in the other instance. In both instances, the knife is carried on a rotating tool holder and interfaces with a rotating cutting edge on the mandrel thereby introducing requirements for timing and spacing between the two in a dynamic fashion. Further, these devices both use a knurling tool mounted adjacent the rotating knife blade to engage, break and knurl the severed ring. No positive location provision is made to handle the knurled strip once it is ejected from the knurling tool. The knurled strip merely falls away.